1. Field of the Invention
This invention relates, generally, to the art of prosthetics. More particularly, it relates to a locking device that is laminated within the hard socket of a prosthetic limb.
2. Description of the Prior Art
The residual limb or stump of an amputee is typically placed into a cushioned liner having an open proximal end for receiving the stump and a closed distal end to which is attached a metallic locking pin that extends therefrom along the longitudinal axis of the liner.
The liner may be formed of any suitable material, although the present inventor has recently introduced a unique liner made of transparent silicone that includes a novel means for interlocking the metallic locking pin to said silicone liner.
The stump, protected by the liner, is inserted into the hard socket of a prosthetic limb, and the locking pin extending from the distal end of the liner engages a locking device which is laminated into said hard socket. The locking device secures the pin and hence the liner to the prosthesis; unlocking means are included as a part of the locking device so that the amputee may remove the prosthesis when desired.
The locking device is in turn attached to an adapter plate which attaches to an alignment pyramid. Thus, the art teaches that three pieces are needed to connect the liner to the prosthetic device, i.e., the locking device, the adapter plate, and the alignment pyramid.
There are several drawbacks of the known three piece design. For example, the three pieces are heavy, expensive to manufacture, and have a substantial length or height when assembled together to form the locking means. Such length prevents the locking means from being used in prosthetic sockets that lack sufficient space to accommodate such lengths.
The earlier device also tends to rotate with respect to the prosthetic socket within which it is embedded.
What is needed, then, is an improved locking device. An improved device would have fewer parts so that it would be less expensive to manufacture, would weigh less so that it would place less burden on its user, would have a truncate extent relative to the elongate extent of the known devices so that it could be used even with sockets having limited space for the accommodation of locking devices, and would not rotate with respect to the prosthesis so that it would not require frequent adjustment or repair.
However, in view of the prior art at the time the present invention was made, it was not obvious to those of ordinary skill in this art how an improved device could be provided.